Multiple life light bulb



Aug; 31, 194 8. L s. J. MENO ETAL MULTIPLE LIFE LIGHT BULB Filed Aug.:50, 1946 I NYENTORS \J- R. CAVANAGH .s.u. MEMO A'I'T'YS A Patented Aug.31, 1948 MULTIPLE LIFE LIGHT BULB Stanley Joseph Mono and John RichardCavanagh, Toronto, Ontario, Canada Application August 30, 194.6, SerialNo. 693,851

2 Claims. 1 This invention relates to a multiple-life light bulbadaptable primarily for street lighting and the like.

Over the whole continent, the maintenance of street lighting facilitiesrequires the engagement of a large staff of inspectors who continuallymake rounds inspecting and replacing light bulbs along highways andstreets. Often the bulbs are replaced after a certain predeterminedperiod even though a portion of their life remains. Aside from themaintenance and replacing staff required under these conditions, thereare certain instances where a light bulb becoming suddenly defectiveresults in actual danger to persons. In a moment of reflection many suchinstances come to mind and it is readily realized that in somesituations a real danger exists where a light bulb fails.

It is, therefore, the prime object of the present invention to provide alight bulb which is characterized by a plurality of filaments mounted ina single glass enclosure, each of the filaments being connectableconsecutively and automatically when each successive filament burns out.

A further object of the present invention is to provide a plurality lifelight bulb as formerly described, which due to its use will enablemunicipalities to cut their lighting service stafis substantially inhalf.

A still further object of the present invention is to provide a lightbulb of this type which, although substantially replacing a plurality oflight bulbs, is less expensive to manufacture than that same plurality,yet which may be marketed at substantially the same price as thatplurality due to the conditions formerly described, and further set outhereinafter.

A still further object of the present invention is to provide aplurality life light bulb employing a switch mechanism enclosed withinthe bulb which governs the operation of a plurality of lightingfilaments disposed therein, the said switch mechanism being extremelysimple in principle and design and, therefore, adaptable to massproduction means.

A still further object of the present invention is to provide a lightbulb as herein set out which eliminates any danger to human life orhealth due to failure of a lighting filament.

A still further object of the present invention is to provid a pluralitylife light bulb as formerly described which is adaptable to manyvariations in product design whereby its manufacture is facilitated at aminimum initial outlay.

With these and other objects in view, the present invention generallycomprises a light bulb having a plurality of lighting elements mountedtherein, each of said elements having one end thereof connected to acommon source of current, the other end of each of said elements beingconnectable to a switch mechanism. The elements are thus disposed in thebulb such that they may be connected in parallel by the switch mechanismprovided, but normally are not so connected when the bulb is inoperation. To this end, the first element of the parallel group is connected directly across a source of voltage, its uncommon standard havinga switch means thereto which normally breaks the circuit leading to aparallelly connected clement when the first element is drawing current.

Other objects of the present invention will be revealed by a study ofthe following specification taken in conjunction with the accompanyingdrawing.

In the drawing: 1

Fig. l is a perspective view of a partial interior structure of one typeof conventional light bulb, disclosing elements connected to a commonstandard, the other of said element having its other end connectable tosaid switch means which is normally open when said first element isdrawing current.

Fig.2 is a schematic of the preferred circuit of th present invention.

Referring to the drawings, the inner extruding mounting portion H) of aconventional electric light bulb is shown, having standards ll and [2extending upwardly therefrom. The standards H and I2 are connected tothe socket of the bulb (not shown) in the normal manner. To facilitatethe support of some types of filaments base means [3; which normallymounts supporting wires (not shown) for the element, is shown extendingfrom the glass mount I0.

Connected between the two standards, a conventional lighting filament I4is shown being for further purposes termed the primary element orprimary filament. A stand-01f insulator I5 is mounted on the standard Hand carries a rod l6. One end I 1 of the rod It has a secondary filamentl8 mounted thereon, the latter extending to the common standard [2. Alsomounted on the standard I I, a bi-metal I9 is shown substantiallyenclosing a, portion of the filament I4 in spaced relation thereto andhas its outer end 20 disposed toward the rod It. A contact point 2| ismounted on the free end 20 of the bi-metal I9 and made of tungsten orother suitable material. A cooperating contact means 22 is shown mountedon the upper extremity 23 of the wire I6.

The contacts 2| and 22 in this particular case are normally closed whenthe filament I4 is drawing no current at which time both filaments I4and [8 will be connected in parallel across the standards II and I2.When the standards II and I2 are connected across a source of current,both filaments I4 and I8 will'receive current and emit heat, thefilament I 4 thus causing the bi-metal l9 to uncoil, resulting in anopening of the contacts 2| and 22 and a breaking of the circuit of thefilament Hi.

It is, of course, necessary that the bi-metal is be fashioned in aparticular manner" of suitable materials, for certain conditions must beovercome. Preferably the bi-metal is placed in close proximity to thefilament M as shown and finished to a high polish on itsexterior'surface, whereby it is made almost entirely dependent on:theheat generated by the filament M. The bi-metal must. be disposed inits normal closed position under the operating temperature of the bulbexclusive of the heat generated by the filament H; To this end, theexact nature of the contact point 21 and 22' must be designed to ensureclosure of the circuit involving the filament. l8 under. normaloperating temperatures inth'ebulb assuming filament M has failed. Thecurved nature of the bi-metal I9 results in the presenting. of its outersurface to the radiant heat energy emanating from the filament I8 whenthe latter is drawing current so that the contacts 2! and 22 will notopen during energization of filament I8.

It is intended that the present, disclosure should not be construed aslimiting in any way except as defined by the scope of the followingclaims.

What we claim as our invention is:

1. A plurality life lighting device comprising a primary light emittingfilament connected across a source of current, and a secondary filamentconnectable across said source of current when said primary filamentfails, a bi-metal element mounted adjacent said primary filament at oneend thereof and connected thereby'to said source of current and designedpartially to enclose said primary filament at a predetermined distancetherefrom, said secondary filament and said pri mary filament beingcommonly connected at their one end to said source of current, rod meansmounting the other end of said secondary filament and disposed to engagesaidbi-metal whereby to complete the electrical circuit of saidsecondary filament when said primary filamen't ceases to draw current,insulating mounting 4 means for mounting said rod and disposing thelatter to engage said bi-metal, said bi-metal disengaging from said rodto disconnect said successive filament from its circuit when saidpreceding filament draws current and emits radiant energy, said bi-metalengaging said rod normally after failure of said primary filament andconducting current from said source to said secondary filament when thelatter is emitting radiant energy the exterior surfaces of said bi-metalbeing designed to refiect heat and light, said filaments being disposedin substantially equivalent light emitting positions, whereby onefilament is the equivalent of each other filament in illuminating value.

2. A plurality life lighting device comprising, a primary coiledlight-emitting filament connected across a source of current, asecondary filament connectable across said source of current when saidprimary filament fails, a bi-metal element mounted adjacent a fixed endof said primary filament, a standard mounting the latter, said bi-*neta1element extending therefrom to partially enclose said filament at apredetermined distance therefrom, a standard connecting the other end ofsaid primary filament and one end. of said secondary filament commonlyto said.

source of current, stand-off'insulator means extending from the standardmounting said bimetal, rod means mounted in said. stand-off insulatormeans, said rod mounting the other end of said secondary filament anddesigned also to engage said bi-metal when no current is drawn by saidprimary filament, said bi-metal engaging said rod normally after failureof said primary filament and conducting current fromsaid source to saidsecondary filament, the exterior surfaces of said bi-metal beingdesigned to. reflect heat and light, said filaments being disposed insubstantially equivalent light emitting positions, whereby one filamentis the equivalent of each other filament in illuminating value.

STANLEY J. MENO. J. RICHARD CAVANAGH.

REFERENCES CITED The following references are of record in the file ofthis patent:

